If no further manipulations of the digested DNA are planned, the reaction can be terminated by adding a stop solution. At NEB, we use the following stop solution: 50% glycerol, 50 mM EDTA (pH 8.0), and 0.05% bromophenol blue (10 μl / 50 μl reaction). If further manipulations of the digested DNA are required, heat inactivation (raising the temperature to 65 or 80°C for 20 minutes) is the simplest method of stopping a reaction. Since this method does not work for all restriction enzymes, refer to the catalog information for the particular enzyme(s) you are using. Phenol/chloroform extraction is another means of inactivating a restriction enzyme.